This proposed work is designed to elucidate the biochemical and physiological mechanisms involved in the control of food intake of animals fed disproportionate amounts of dietary amino acids. We intend to determine the location of the critical areas in the central nervous system and/or elsewhere, and the metabolic or other signals as well as the manner whereby the mechanisms of food intake control are triggered when the animals respond to the intake of disproportionate quantities of dietary amino acids. Detailed feeding patterns in terms of changes in feeding parameters (meal size, meal frequency, etc.) will be monitored with computerized electronic recording balances, so as to correlate changes in feeding patterns with changes in metabolic events or key metabolites in the blood plasma, brain or other tissues induced by various experimental treatments involving diets, nutrients or other exogenously introduced substances. Normal intact or lesion bearing animals in areas involved in the control of feeding, as well as animals with chronically implanted cannulae in the brain, blood vessels (carotid artery, jugular or portal vein) or other areas in the animal body, will be used in the experiments and infused with amino acids (isotopically labeled or unlabeled), other metabolites, drugs, neural humors, etc., and the changes in feeding patterns closely monitored. Areas of the brain to be examined include hypothalamic and extra-hypothalamic neural areas such as anterior prepyriform cortex, the medial amygdala, the lateral septum, the dorsal-lateral hippocampus, as well as the midbrain.